Hydrology, activity, and heat flow of the Steamboat Springs thermal system, Washoe County, Nevada

Hydrogeologic appraisal of the Klamath Falls geothermal area, Oregon

“…If this supposition is true, the meteoric waters, in their passage through the geothermal reser voir, acquire increased amounts of calcium, sodium, potassium, chloride, sulfate, and silica, while concen trations of bicarbonate decrease somewhat and mag nesium is reduced almost to zero. Changes of this kind are commonly found in hot-water geothermal systems (White, 1970), and they are compatible with the as sumption that the Klamath Falls thermal waters are locally derived.…”

“…These waters have apparently been enriched in 18O during their passage through the geothermal reser voir, with increases in 818O ranging from 0.8 to 1.4 %o. The increase is small compared to that observed in high-temperature geothermal systems such as Steam boat Springs, Nev. or The Geysers, California, which have increases in 818O as great as 3 to 5 %<> (White, 1968). The isotope data suggest, therefore, that the Klamath Falls hot waters have not equilibrated at ex tremely high reservoir temperatures, or, alternatively, that they have been diluted by mixing with cooler wa ters.…”

“…High ratios of calcium to magnesium are generally charac teristic of high-temperature geothermal systems, but may occur at temperatures as low as 100°C (White, 1970, p. 70). High ratios of sodium to potassium also imply elevated reservoir temperatures, but suggest that the waters equilibrated at temperatures not much higher than the measured temperatures (Mariner and Willey, 1976;White, 1970). Ratios of Na/K are strongly influenced by the amount of available calcium in the water and cannot be relied upon as geothermometers in waters, such as those at Klamath Falls, for which molal ratios of VCa/Na are greater than one and in dicated reservoir temperatures are low (Fournier andTruesdell, 1973, p. 1272).…”

“…The large Basin and Range faults that bound the Klamath Falls graben could provide the required channels as similar faults are assumed to do elsewhere in the Basin and Range province (White, 1968;Olmsted and others, 1975). The depth that would have to be reached by the Klamath Falls thermal waters in order to attain a temperature of 150°C is 15,000 feet if the geothermal gradient is as low as 30°C per kilometer.…”

Oxygen isotope evidence for large-scale interaction between meteoric ground waters and Tertiary Granodiorite Intrusions, Western Cascade Range, Oregon

“…One of the major difficulties in interpreting such systems has been the problem of heat transfer between the heat source (i.e., the intrusion) and the H20. This is generally shown as occurring by simple heat conduction [White, 1968, Figure 3]. On the basis of the data in the present study, the heattransfer problem can probably be adequately explained by migration of the H20 directly into the heat source itself.…”